The present disclosure relates generally to casting, and more particularly, to a lost foam casting of a low alloy steel having carbon content in a range from about 0.1 to about 0.4 percent.
Generally, sand casting requires a plurality of cores for casting complex structure such as turbine shells, turbochargers, crankcases, blowers and the like. The usage of plurality of cores increases material and labor cost, and may also result in long lead time in casting.
Lost foam casting may be used to address the problems related to cost and lead time. However, the casting obtained through the lost foam casting may have excessive carbon content. Further, the lost foam casting uses green bonded sand as backup medium within a sand casing, which may produce gaseous product or bubbles when a molten metal is poured into the mold, thereby entrapping the gaseous product within the casting. The carbon pickup and gas entrapment in the lost foam steel casting are caused due to incomplete foam removal before the molten metal solidifies within the mold. The retained foam generates carbon black and the entrapped gases redistributed inside the casting causes generation of higher local carbon content than the required limit.
Further, the molten metal poured in the mold may also react with the green bonded sand resulting in the fusion of the sand to the casting, thereby creating sand burns which may degrade the surface of the casting. The process of removal of the sand burns from the casting may further add to the process cost.
Thus, there is a need for an enhanced casting process for producing a low alloy steel having a very low carbon content.